Natural Navigational Guidance

ABSTRACT

Natural navigational guidance, provides enhanced guidance instructions that take advantage of unique geographic features along a navigated route to specify maneuver points. Guidance points are clearly visible, unambiguous, and locally unique features in the geography of the maneuver area that can be used to aid the user in discovering the place where the maneuver point is. Within a guidance point selection area, a specific guidance point type has a more strict area within which it can be used. A natural guidance point selection area for an upcoming maneuver to be navigated is determined, and a unique geographic feature within the determined natural guidance point selection area is selected as a natural guidance point for navigation of the upcoming maneuver. A turn-type natural guidance point for an upcoming maneuver to be navigated is generated when the user device is within the natural guidance point selection area.

The present invention claims priority from U.S. Provisional No. 61/591,148 to Clark et al., entitled “Natural Guidance”, filed Jan. 26, 2012; from U.S. Provisional No. 61/591,151 to Clark et al., entitled “Lane Guidance”, filed Jan. 26, 2012; and from U.S. Provisional No. 61/711,546 to Clark et al., entitled “Natural and Lane Guidance”, filed Oct. 9, 2012, all of which are expressly incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to navigation systems, and more particularly to wireless navigation systems such as on a Smartphone.

2. Background of Related Art

Natural guidance is known, e.g., as disclosed in NAVTEQ's natural guidance documentation “62d Product Variations Natural Guidance.pdf”, the entirety of which is incorporated herein by reference. However, the NAVTEQ approach is not ideal.

SUMMARY

In accordance with the principles of the present invention, a method of providing natural navigational guidance to a user device comprises determining a natural guidance point selection area for an upcoming maneuver to be navigated. A geographic feature within the determined natural guidance point selection area is selected as a natural guidance point to be identified for navigation of the upcoming maneuver. A turn-type natural guidance point for an upcoming maneuver to be navigated is generated when the user device is within the natural guidance point selection area.

BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of the present invention become apparent to those skilled in the art from the following description with reference to the drawings, in which:

FIG. 1 shows Guidance Points selected according to a priority table, which is server configurable and can be updated without requiring a new client build. Different types of Guidance Points have varying priorities according to how close they are to the maneuver point and their position with respect to it. Priorities are determined depending on the position of the guidance point with respect to the maneuver point.

FIG. 2 shows natural guidance using an “end of the road” guidance point, in accordance with the principles of the present invention.

FIG. 3 shows natural guidance using a bridge, in accordance with the principles of the present invention.

FIG. 4 shows natural guidance using street counts, in accordance with the principles of the present invention.

FIG. 5 shows natural guidance using railroad tracks, in accordance with the principles of the present invention.

FIG. 6 shows natural guidance using stop signs, in accordance with the principles of the present invention.

FIG. 7 shows natural guidance using traffic lights, in accordance with the principles of the present invention.

FIGS. 8A and 8B show exemplary lane guidance for taking a right turn depicted in a color different from that used to depict the ongoing lanes, in accordance with the principles of the present invention.

FIG. 9 shows guidance for taking a left turn, in accordance with the principles of the present invention.

FIG. 10 shows the display of the prominent Visual Lane Guidance in a 3D vector view, in accordance with the principles of the present invention.

FIG. 11 shows an exemplary regular maneuver (no lane guidance) using the inventive lane guidance widget which displays maneuvers using the inventive TrueType lane guidance font, in accordance with the principles of the present invention.

FIG. 12 shows the display of the prominent Visual Lane Guidance in a 2D vector view, in accordance with the principles of the present invention.

FIG. 13 shows the display of the prominent Visual Lane Guidance in an ECM view, in accordance with the principles of the present invention.

FIG. 14 shows the display of the prominent Visual Lane Guidance in a dashboard view, in accordance with the principles of the present invention.

FIG. 15 shows the various points at which announcements are made, and what other things depend on those points, in accordance with the principles of the present invention.

FIG. 16 depicts an exemplary ‘slot’ definition to determine whether there is sufficient time of travel to play a traffic announcement in between navigation announcements, in accordance with the principles of the present invention.

FIG. 17 shows the appearance of a freeway exit, and a suggested place for the exit number in the turn list, in accordance with the principles of the present invention.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The Natural and Lane Guidance feature includes enhancements to the way directions are being provided to the user. Natural Guidance improves instructions by using features along the route as reference points instead of just mentioning street names and distances. Lane Guidance improves the user experience when driving on freeways and other wide roads by providing lane information visually and verbally. Guidance is improved to provide better, more concise instructions.

Glossary

Term Definition Guidance Point A feature along the route that is used in guidance as a reference point for a maneuver Guidance Point Area The area within a maneuver where the routing engine is allowed to pick up Guidance Points for that maneuver MJO Motorway Junction Object

Extensive usability testing showed that providing navigation instructions in a more natural and human-like manner was highly desired by end users. Additionally, user feedback and observed behavior showed that when navigating, most people kept their wireless device (e.g., smartphone) in a place where the screen is not in clear view, so it is important to provide clear and concise voice instructions.

The Natural Guidance feature provides enhanced guidance instructions that take advantage of features along a navigated route to specify maneuver points using easy to understand reference points. The feature makes use of additional rules extracted from the map data (including additional data from NAVTEQ's Stop signs and Traffic lights products).

Ideally the natural guidance feature does not add new types of guidance prompts. Instead, it provides enhancements to existing prompts (Continue/Prepare/Turn) by sometimes replacing terse instructions based on distance with more clear instructions based on features around the maneuver that are clearly visible and easy to find by the driver.

Guidance Points are features in the geography of the maneuver area that can be used to aid the user in discovering the place where the maneuver point is. Since Guidance Points are supposed to aid the user in locating a particular position, they are ideally clearly visible and unambiguous to ensure they will not cause confusion.

The following are examples of the various types of elements that could be used as Guidance Points:

-   Natural elements such as lakes, mountains, hills or other kinds of     formations that can be clearly spotted from the road (not used in     present embodiments), -   Buildings that are easily identifiable, such as towers, churches,     gas stations, restaurants, etc. (not used in present embodiments), -   Traffic lights, when clearly identifiable, -   Stop signs, when clearly identifiable, -   End of the road, -   Railroad tracks, -   Bridges, and -   Crossing streets

While many guidance points are present in the map data, they are only relevant to a specific maneuver if they meet very strict criteria. Those criteria are clearly described herein.

Guidance Point Area

To be referenced in a “Prepare” or a “Turn” instruction, a Guidance Point of a certain type must be unique within a region called “Guidance Point Area”.

FIG. 1 shows Guidance Points selected according to a priority table, which is server configurable and can be updated without requiring a new client build. Different types of Guidance Points have varying priorities according to how close they are to the maneuver point and their position with respect to it (if applicable).

In particular, as shown in FIG. 1, the Guidance Point Area starts at point NB and ends at point NE. NB is calculated using the same as the “Prepare” distance used by the client. The distance is calculated using the speed category of the segment, as the routing engine does not know the speed of the vehicle. The following table shows values at common speeds for the cases where the maneuver is in a surface street, a highway, or the destination:

Speed mph Distance for N_(B) in meters (Normal-Freeway-Destination) 25 411.23 1035.11 668.17 35 527.44 1321.16 775.43 45 643.64 1607.20 882.70 55 759.85 1893.24 989.97 65 876.05 2179.29 1097.23

NE is placed just past the maneuver point, such that it covers the opposite side of the street (corner) of the maneuver point. Note that this allows Guidance Points to be placed past the maneuver point, but only if they are immediately adjacent to it.

Guidance Point Selection Area

Within the Guidance Point Area, a specific guidance point type has a more strict area within which it can be used. For example, Traffic Lights and Stop Signs are only useful if they are on the maneuver point. Other guidance points may be allowed a bit farther from the point. This type-specific area is called the Guidance Point Selection Area and is defined as follows:

Guidance # Point type Turn point area Prepare to area 1 Natural Must be adjacent to the turn Yes guidance point, no crossing streets in points from between NAVTEQ 2 Railroad tracks Must be adjacent to the turn Yes point, no crossing streets in between 3 Traffic Lights Must be on the turn point Not used. Can be combined with #1, 2 or 6 4 Stop sign Must be on the turn point Not used. Can be combined with #1, 2 or 6 5 End of the road Must be on the turn point Not used. Can be combined with #1, 2 or 6 6 Bridge Must be adjacent to the turn Yes point, no crossing streets in between 7 Street count Up to 2 crossing streets Not used (“Take the third street”), each street at most 75 meters (~250 ft) from the next one

Guidance Point Selection Rules

Selection of guidance point is governed by several rules aimed at finding the best possible reference point to aid the user in understanding the maneuver. The following are the general rules:

There can only be one or two guidance points for each maneuver. It is expected that most maneuvers will have zero or one guidance points. A second guidance point is supported for some guidance point types to allow the case where directions can be improved by allowing the prepare instruction and the turn instruction to reference different guidance points;

Turn Guidance points can only be referenced if they are positioned within the Guidance Point Selection Area for the maneuver;

Prepare Guidance Points can be referenced outside the Guidance Point Selection Area only if they are not used as Turn Guidance points;

A guidance instruction cannot reference a guidance point that is behind the user's current position;

Prepare announcements can reference a guidance point anywhere in the Guidance Point Area;

Turn Announcements can only reference guidance points at or immediately before the turn. Note that “at the turn” includes guidance points that are past the maneuver point, but adjacent to it; and

The type of a “candidate” guidance point must be unique within the Guidance Point Area for it to be referenced in the maneuver instruction. This means that if there is more than one guidance point of that type in the Guidance Point Area, none of them can be used.

Guidance Point Priority

The order of priority of selection of priority points in the exemplary disclosed embodiments is as follows:

(1) Traffic light;

(2) Stop sign;

(3) End of the road;

(4) Railroad tracks at position 1 in FIG. 1;

(5) Railroad tracks at position 0 in FIG. 1;

(6) Bridge; and

(7) Street count—should only be used if the streets are less than 75 meters of each other.

Usage Rules

Continue instructions: Guidance Points are not referenced in Continue instructions.

Prepare instructions: Guidance Points are referenced in the Prepare instruction if available for the maneuver (marked use-for-prepare in the protocol).

Turn instructions: Guidance Points are referenced in the Turn instruction if available for the maneuver (marked use-for-turn in the protocol).

Stacked maneuvers: Guidance Point may be more beneficial than using the street name, as stacked maneuvers can be handled in different ways, e.g.:

Using Street Name

-   Product says get ready for the stacked maneuver.

Natural Guidance Points End of the Road

FIG. 2 shows natural guidance using an “end of the road” guidance point, in accordance with the principles of the present invention.

In particular, as shown in FIG. 2, natural guidance at the end of a road can be used when the user device dead ends into a perpendicular road, e.g., with the guidance “Turn right at the end of the road”.

Bridge

FIG. 3 shows natural guidance using a bridge, in accordance with the principles of the present invention.

In particular, as shown in FIG. 3, bridges can be used as Guidance points when the user device is being driven on a bridge and the turn street is the first street at the end of the bridge and the end of the bridge is in the Guidance Point Area. At this point, as depicted in FIG. 3, the natural guidance may be, e.g., “Turn right after the bridge onto Crown Point Drive.”

Street Counts

FIG. 4 shows natural guidance using street counts, in accordance with the principles of the present invention.

In particular, as shown in FIG. 4, street counts can be used as a Guidance point when adjacent streets are very close together, making it unclear to the user device on which street to turn and the streets are within the Turn Instruction Distance and they are legal to turn on. In such case, as depicted in FIG. 4, the natural guidance may be, e.g., “Take the 2^(nd) right and enter the highway.”

Train Tracks

FIG. 5 shows natural guidance using railroad tracks, in accordance with the principles of the present invention.

In particular, as shown in FIG. 5, railroad tracks can be used as Guidance points when the railroad tracks physically cross the street on which the user device is travelling and the crossing is within the Guidance Point Area and the turn street is the first one after the tracks.

Exemplary natural guidance in this scenario is, for a user device travelling East (A) in FIG. 5: “Turn left after the railroad tracks onto Knode Avenue”, or for a user device travelling West (B): “Take an immediate left turn after the train tracks”.

Stop Signs

FIG. 6 shows natural guidance using stop signs, in accordance with the principles of the present invention.

In particular, as shown in FIG. 6, stop sign data can be used as a Guidance Point when the stop sign is in the direction of travel and the street the user device must turn on is at the stop sign and there are no other stop signs on the user device's route within the Guidance Point Area that are applicable to the direction of travel. Exemplary natural guidance is: “Turn right at the stop sign onto Dylan Avenue.”

Traffic Lights

FIG. 7 shows natural guidance using traffic lights, in accordance with the principles of the present invention.

In particular, as shown in FIG. 7, traffic lights data can be used as a Guidance Point when the street the user device must turn on is at the traffic light and there are no other traffic lights on the user's route within the Guidance Point Area. In such scenario, the natural guidance may be “Turn left at the traffic light onto Alicia Parkway.”

Audible Guidance Prompts Timing Configuration

The timing for audible guidance is configurable. The configuration is dynamically done through the server. The timing of announcements can potentially change based on the presence of the following types of information: Lane Guidance, Natural Guidance, and Normal Guidance.

Prompt Length

The client performs calculations to determine the length of the message that is played, and adjusts the timing of the play based on when the play will end as opposed to where it will start. This means that longer messages start playing earlier.

Guidance Points and Lane Guidance

To keep voice prompts clear and concise, the system does not provide natural guidance and lane guidance in the same voice prompt. On highways, lane guidance has precedence over natural guidance, and on surface roads, natural guidance has precedence over lane guidance. In both cases, lane guidance visual information is shown if available. If the client cannot determine if the current road is a highway or a surface road, it is up to the routing engine to implement the priorities described by not including natural guidance in a highway maneuver that contains lane guidance. The client always gives priority, to natural guidance if available.

Examples:

On a surface road, the application prompts the user device to “Turn left at the traffic light onto Aliso Viejo Parkway” instead of “Use the left two lanes and turn at the traffic light onto Aliso Viejo Parkway.”

On a freeway, the application prompts the user device to “Use the left two lanes and exit the freeway at El Toro road” instead of “Use the left two lanes and exit the freeway after the blue building on the right at El Toro road”.

Voice Lane Guidance

Voice Lane Guidance is provided if available, subject to the following conditions:

Data for the road segment is available in the lane guidance database provided by the map data provider.

Only Prepare and Turn instructions; Continue instructions do not use lane guidance.

Stacked instructions use Lane Guidance as available for the two maneuvers.

If the exit lane(s) are not the right/leftmost lanes, then voice lane guidance is skipped and normal prompts is used instead. The visual lane guidance still shows the correct lanes to take, but the announcement is skipped as it would be too complicated.

To determine if the announcement can be made, the client counts the lanes (by looking at the number of lane-guidance-item elements present in the lane-info element for the maneuver), then evaluates if the position of the selected lanes is on either side or in the middle. If the calculated position cannot be described (using the lane positioning identifiers) then the announcement is not provided and the standard straight/right/left announcement is provided instead.

Example: “Use the second lane from the right . . . ” is too complicated, so the system will use the normal “Turn right . . . ” instead.

Lane Positioning Identifiers

Left Center Right Left Lane Center lane Right Lane (left-lane) (center-lane) (right-lane) (only one lane) there are lanes on both sides of (only one lane) Left 2 Lanes the maneuver point and only Right 2 Lanes (left-2-lanes) one lane in the center to (right-2-lanes) (2 lanes available) complete the maneuver (2 lanes available) Left 3 Lanes Center lanes Right 3 Lanes (left-3-lanes) (center-lanes) (right-3-lanes) (3 lanes available) there are lanes on both sides of (3 lanes available) Left 4 Lanes the maneuver point and multiple Right 4 Lanes (left-4-lanes) lanes in the center to complete (right-4-lanes) (4 lanes available) the maneuver (4 lanes available)

Adjacent Exits

Voice Lane Guidance is not given in situations where exits and off-ramps are in close proximity to each other and share the same line information.

Clipping

Announcements are never clipped. The client calculates the announcement length, and moves the announcement earlier to ensure that it fits the available time.

Visual Lane Guidance

The visual lane guidance feature enhances the maneuver display information by incorporating full display of the available lanes in the freeway, when available in the map data. An otherwise regular turn icon display is replaced with a variable width image that grows to show all available lanes, highlighting the ones the user device needs to use to complete the maneuver.

Divider Types

The protocol provides the following divider types to the client. Only a small subset is usually used.

long-dash-divider double-solid-divider single-solid-divider solid-dash-divider dash-solid-divider short-dash-divider shaded-area-divider block-dash-divider physical-divider double-dash-divider no-divider crossing-alert-divider center-turn-line-divider

Direction Categories

The protocol provides the following direction types to the client, which can be combined as needed. A set is provided for selected directions (thos that are part of the maneuver) and another one for unselected. Directions can be combined, but not all combinations are valid.

straight-arrow slight-right-arrow right-arrow hard-right-arrow u-turn-left-arrow hard-left-arrow left-arrow slight-left-arrow merge-right-arrow merge-left-arrow merge-lanes-arrow u-turn-right-arrow second-right-arrow second-left-arrow

Display

To enable this display, the protocol is enhanced to provide the additional lane information, and the client is enhanced to dynamically build the lane display using a custom TrueType font that can be scaled to suit any display.

Lane Font

A new lane TrueType font was created to enable the display of the lane guidance image. TrueType is an outline font standard. The font provides individual characters that represent each possible line situation, and which can be “printed” together to form the current lane configuration for the maneuver. Since TrueType fonts are vector-based, they can be used to generate the lane images at any size, in a platform-independent fashion.

The lane font has direction arrows, which can be combined to form composite arrows; and additional direction arrows as needed to allow replacement of the routing icons currently in use. Lane dividers may also be implemented if desired.

Font Mapping

To map the maneuver commands to the corresponding font code, the following exemplary table is used.

Command Code Image Command Code Image Command Code Image EC. EN. EX. EC.L EN.L EX.L EC.R EN.R EX.R FE. KP. RE. FX. KP.L RX.1-10 PE KP.R RT. TR.L MR.L DT. TR.R MR.R DT.L UT. NC. DT.R NR. BE. DT.U NR.L BE.L TE. NR.R BE.R TE.L ES. EE. TE.R ES.L EE.L TI. ES.R EE.R TI.S ER. TC. SC. ER.L TC.S SC.S ER.R OR.

Building the Image

The client builds the image by printing characters next to each other using the new TrueType font and a few rules. Each character can be regular or highlighted. Highlighting is used to convey where the driver should be. Elements such as lane dividers and direction arrows can be drawn in a different color.

For instance, FIGS. 8A and 8B show exemplary implementation s of lane guidance for taking a right turn depicted in a color different from that used to depict the ongoing lanes. Double yellow lines may be shown as depicted in FIG. 8A or 8B, as can be highlighted lines. Arrows can be combined to form new composite arrows, e.g., the straight arrow plus a slight right arrow in the example of FIG. 8A.

Timing

The timing for visual lane guidance is configurable. The configuration is dynamically accomplished through the server.

Visual Lane Guidance is displayed at the same time that voice Lane Guidance is announced.

View Support

Visual Lane Guidance is displayed in the following navigation views: 3D perspective, 2D perspective, and Dashboard. Preferably Visual Lane Guidance is not integrated with the List view.

FIG. 9 shows guidance for taking a left turn, in accordance with the principles of the present invention.

In particular, as shown in FIG. 9, a new visual lane guidance widget is dynamically generated using a TrueType font instead of the conventional routing icon images. It also uses (when available) lane guidance information to show additional information for the upcoming maneuver.

Data used by the visual lane guidance widget comes from the following sources:

NextTurnDistance is calculated by the navigation engine.

The NextTurnImage depends on whether or not lane guidance is available, which can be queried via a new isLaneInformationAvailable method in the NavigationState class. If Lane guidance is available then the information comes from the lane-info element in the maneuver, which is provided via the new LaneInformation class obtained from the NavManeuver class via the new getLaneInformation method. If Lane guidance is not available then the information comes from the command attribute in the nay-maneuver element (no changes). The client then maps the command to the appropriate character code used to represent the icon.

The StackedTurnInfo is displayed when the stack-advise element is present in the nay-maneuver and the client decides to show the stacked maneuver.

The StackedTurnImage is obtained based on the command attribute of the following nay-maneuver when StackedTurnInfo is displayed and is drawn in a similar way to the NextTurnImage. Lane guidance information is not used in this case.

View Integration

The display of the Visual Lane Guidance is preferably prominent and integrated well with the following views and elements on the screen: 3D vector view (FIGS. 10A and 10B); 3D vector view with stacked maneuver (FIG. 11); 2D vector view (FIG. 12); SAR; ECM view (FIG. 13); MJO view; and dashboard view (FIG. 14).

The present invention provides navigation guidance that makes instructions as succinct as possible; deliver the information in a more human-like manner; eliminate unnecessary announcements; and keep announcements that help maintain the user device on the right path, especially in situations where there could be confusion.

Announcements

The following terminology is used to describe navigation announcements: Continue announcement; Prepare announcement; and Turn announcement.

The Continue announcement is the first instruction in the series leading to a maneuver, usually following the turn instruction from the previous maneuver, and is only given when there is enough distance in the segment to allow for three instructions. The purpose is to provide to the user device how long of a drive remains until the next maneuver point is hit. The Continue announcement is used to inform the user of the distance to the next turn or their destination.

The Prepare announcement is a second instruction in the series, usually following the continue instruction. Its purpose is to help the drivers position themselves in the correct lane and prepare for the actual maneuver.

The Turn announcement is a final instruction in the series, in most cases following the Prepare instruction. Its purpose is to instruct the user to perform the maneuver.

The Continue announcement is formatted in the exemplary embodiments as: “Your next turn is in <x> miles” when there is an upcoming maneuver, or “Your destination is in <x> miles” when the destination is approaching. To make the announcement sound more natural, the distance is rounded up to the nearest ½ mile increment when the distance is above two miles and to the nearest ¼ mile increment when the distance is less than 2 miles. If the application is set to use the metric system, then the rounding is to the nearest ½ kilometer.

The Prepare announcement is used to inform the user that the maneuver turn is approaching and to provide additional guidance information if available. The Prepare announcement does not contain distance to the turn.

The Turn announcement informs the user to make the maneuver. The Turn announcement does not contain distance to the turn.

Timing and Positioning of Announcements

The timing of navigation announcements depends on the type of road being traveled, the current speed of the vehicle and the length of the announcement itself. As part of the Natural and Lane Guidance effort, some key changes are made in how the timing is calculated.

FIG. 15 shows the various points at which announcements are made, and what other things depend on those points. In the disclosed embodiments, the routing engine defines the maneuvers, but the client uses the information provided to calculate when and where to provide announcements. For Natural Guidance, the routing engine calculates the

Guidance Point Area for each maneuver, which depends on the speed of the segment.

The following are key changes from the otherwise conventional implementation:

-   The playback time for all messages is now calculated ahead of time     by the client and used in the timing calculations. -   Clipped messages are avoided in most situations. -   The Prepare instruction distance now marks the end of the prepare     message in the automatic mode. -   The Turn instruction distance now marks the end of the turn message     in the automatic mode. -   Traffic announcements are only allowed (if they fit completely with     an additional buffer as shown and described with respect to FIG. 15)     in the time between the continue message and the prepare message, or     in the time between the prepare message and the turn message. -   Recalc announcements no longer result in the prepare message and the     turn message possibly played ahead of time. If the recalc happens     such that a message cannot be immediately played (because it doesn't     fit), then the application will wait until the correct message can     be played. Repeated messages are removed. -   Since the prepare instruction distance and turn instruction distance     now specify the end of the prepare and turn message announcements,     their positions may be moved later as no longer need to account for     long messages.

Distance Calculations

The client currently uses the following formula to calculate the distance for the announcements:

Announcements Distances

Name Description A Show Turn The distance at which the specific turn Distance information is displayed. B Announce The distance at which the prepare message is Distance allowed to be repeated when the user device reaches the Prepare Instruction Distance. Note: this is no longer needed with the timing changes. C Stacked The distance at which a stacked instruction is Instruction displayed. Distance L Lane Guidance The distance at which Lane Guidance is Distance displayed if available. D Prepare Instruction The distance at which the prepare message for Distance the upcoming maneuver completes playing. E Prepare Minimum The minimum distance at which the user device Distance is instructed to prepare for the next maneuver. This is meant to keep the prepare and the turn messages from occurring back to back. Note: this is no longer needed with the timing changes. F Turn Instruction The distance at which the turn message for the Distance upcoming maneuver completes playing. G Maneuver Point The point at which the turn occurs.

Announcement Distance Calculation

The values for each of these distances are calculated based on the current speed of the user according to the following formula:

D=(S×A+B)×M

Variable Name Description D Distance The desired distance. S Speed The current speed (if known), otherwise the default speed for the current maneuver.. A Base Multiplier The basic multiplier factor derived from the DOT study. See the following tables for specific values. B Base Addition The basic additive factor derived from the DOT study. See the following tables for specific values. M Multiplier The final multiplier factor. The specific multiplier for distance to be calculated. See the following tables for specific values.

Announcement Distance Values

The following table lists the specific values for the Base Multiplier (A) and Base addition (B) for the various types of maneuvers:

Type Base Multiplier Base Addition Normal 8.0 37.144 Highway 8.0 40.0 Destination 3.0 50.0 The following table lists the specific values for the final multiplier (M) for the various types of maneuvers:

Stacked Lane Prepare Type Announce Turn guidance Prepare Minimum Turn Normal 6.9 3.25 0 3.25 3 0.7 Highway 8.05 8 0 8 4 1.5 Desti- 86.25 0 0 8 5 0.5 nation

Guidance Point Area Calculation

To calculate the extent of the Guidance Point Area, the routing engine obtains the position for N_(B), the start of the Guidance Point Area. The other end of the Guidance Point Area (N_(E)) is defined by the geography around the maneuver point, as it includes potential guidance points that are adjacent to the maneuver point but immediately after it.

Changes in Timing

The inventors hereof recognized that the conventional announcement method has some issues which are fixed and/or improved upon with the present invention. The client does not calculate how long an announcement prompt is before playing it. Also, announcements start at well-defined points but have variable length, so the end point is unpredictable, forcing longer-than-needed times before the turn to accommodate for the longest messages. Moreover, the time between the prepare prompt and the turn prompt can be small, and it often collides with traffic messages, which are then clipped (and later replayed) to allow for timely playback of the turn message.

FIG. 16 depicts an exemplary ‘slot’ definition to determine whether there is sufficient time of travel to play a traffic announcement in between navigation announcements, in accordance with the principles of the present invention. In particular, as shown in FIG. 16, the present invention modifies its timing of announcements as follows:

All messages including traffic are pre-processed at the start of the maneuver (ahead of the time of play) and their playback time is calculated.

The start of playback for automatic prepare and turn messages is moved such that the end of the message (as opposed to the start) coincides with the prepare/turn distance. The playback distance is calculated using the message play time and the vehicle's current speed. The calculated distance is added to the announcement distance to calculate the adjusted announcement distance. In the event that GPS fixes cease to be received temporarily (for example inside a tunnel) and the next received fix is past the desired start of playback, the prepare message is played only if the current position plus the calculated distance used to play the message at the current speed allows for at least a 2-second gap before the maneuver point. Also only if the message references a guidance point, the point must be positioned after the expected end of playback. If this is not the case, but there is still time to play the message, the client reprocesses the message without using the guidance point.

The turn message is always played as long as the user is before the maneuver point. The content of the announcement is reduced as much as needed to make it fit the available time, but the message is played regardless of whether it fits the slot.

Any real-time audio snippets (such as time or distance) are re-processed just before playback for accuracy. Since distances are removed from Prepare and turn messages, this is not likely to be a common occurrence.

The announcement distance parameter is reworked to account for the difference and move the announcement end points closer to the maneuver point.

The (expected) time between the end of the continue announcement and the start of the prepare announcement is calculated. If the Continue announcement is skipped, then the Prepare announcement is moved up to the start of the maneuver, effectively removing the first traffic announcement slot.

The (expected) time between the end of the prepare announcement and the start of the turn announcement is calculated.

If there are pending traffic announcements, the client checks to see if the announcements fit with more than 2 seconds buffer in the available time between announcements. If an announcement fits between the continue and prepare announcements, it is played one second after the continue announcement completes. If an announcement fits between the prepare and turn announcements, it is played one second after the prepare announcement completes. If the announcements don't fit, they are queued, and attempted to fit in again for play during the next maneuver.

Prepositions

Prepositions are used to give the position of the maneuver relative to the Guidance point. The current list of prepositions is extended as needed to cover the updated instructions.

Maneuver Direction

The following maneuver directions are available for guidance:

-   Left -   Slight Left -   Hard Left -   Right -   Slight Right -   Hard Right -   U-Turn -   Continue On -   Stay

Direction information is carefully considered, and modifiers such as slight or hard are used only as needed to aid in the user's understanding of the maneuver under special conditions.

Concatenation

Guidance prompts are usually generated by concatenating audio snippets that are part of the application's data with street names that are downloaded as part of the nay-reply. For instructions where distances are not referenced, all combinations of instructions prior to the street name are pre-processed. Distances will not usually be required for Prepare To and Turn instructions.

Special Processing of Audio Fragments

To provide better speech quality, some longer than needed audio phrases are generated. For example, the sentence “Get ready to keep left at the fork and take Main street” is usually broken into “Get ready to”, “keep left”, “at the fork”, “and take” and “Main street”, with the street name being downloaded from the server. While this saves considerable space, it breaks the context of the sentence for the speech generator and results in less natural pronunciation.

To maintain flexibility while also allowing for improvement in quality, a new method is used to concatenate the audio fragments and allow for easy joining of fragments into longer fragments. Using the example above, each audio fragment has a “sound id” which maps to the filename. For example the mapping may be as shown in the following table:

Text sound ID Filename Get ready to get-ready-to get-ready-to.aac keep left keep-left keep-left.aac at the fork at-the-fork at-the-fork. aac and take and-take and-take.aac Main street <dynamic-id> <dynamic-id>.aac

If it is desired to join the fragments into a single fragment for better pronunciation quality, the entire fragment “Get ready to keep left at the fork and take” may be generated as a single audio file, but be named such that the sound IDs of the individual fragments are joined using the ‘+’ character. In the example above, the new sound ID representing the larger audio fragment is “get-ready-to+keep-left+at-the-fork+and-take” and the filename is “get-ready-to+keep-left+at-the-fork+and-take.aac”.

To automatically discover these improved audio fragments, the client code attempts to concatenate the pieces and verify if a matching filename exists. Since most compound fragments only have a few components, calculating all possible combinations is a simple and quick process, and the longest available fragments are used.

In the example above, the combinations are:

-   get-ready-to+keep-left+at-the-fork+and-take+<dynamic-id> (all 5) -   get-ready-to+keep-left+at-the-fork+and-take (4 at a time) -   keep-left+at-the-fork+and-take+<dynamic-id> (4 at a time) -   get-ready-to+keep-left+at-the-fork (3 at a time) -   keep-left+at-the-fork+and-take (3 at a time) -   at-the-fork+and-take+<dynamic-id> (3 at a time) -   get-ready-to+keep-left (2 at a time) -   keep-left+at-the-fork (2 at a time) -   at-the-fork+and-take (2 at a time) -   and-take+<dynamic-id> (2 at a time)

So the method is as follows:

Step 1: Take a compound fragment consisting of n pieces.

Step 2: Concatenate the n sound IDs using ‘+’ and see if a filename exists.

Step 3: If found, use that file instead of the individual fragments.

Step 4: If not, repeat the process for each possible subset of n-1, n-2, . . . , 2 consecutive pieces.

Step 5: If a match is found, replace the matched pieces with the new compound piece, and repeat the algorithm with any pieces before and after the replaced piece containing two or more pieces.

Step 6: If no matches are found, concatenate the individual pieces.

This method is run for any subset of the sentence containing 2 or more sub-elements, so for the example above, it should be possible to end with “get-ready-to+keep-left”, “at-the-fork+and-take” and “<dynamic-id>” being used instead of the original individual pieces. Also, since the method starts with longest combinations first, priority is given to those over smaller ones, which is the desired effect. Lastly, the method does not differentiate between base voices and voices downloaded from the server. Though in the disclosed embodiments downloaded voices may never match, a feature may be added to allow requesting compound voices dynamically, or to generate the voices using text to speech.

Freeway Exit Numbers

When travelling on a freeway, exit numbers are added to the maneuver used to exit the freeway. For example: “Prepare to stay in the left to lanes and take Exit 8, MacArthur Blvd”.

FIG. 17 shows the appearance of a freeway exit, and an exemplary location for an associated exit number, in the turn list, in accordance with the principles of the present invention. The font size of the exit number in the turn bar at the top may be increased to make it more visible. FIG. 17 indicates an exemplary location for an appropriate exit number.

Protocol Changes Announcement-Distance-Parameters Elements

Type Number Description ann-base- 1 Base multiplier for the announcement multiplier distance calculation. ann-base-addition 1 Base addition for the announcement distance calculation. ann-multiplier 1 Multiplier for the announcement distance calculation.

Attributes

Name Type Description none

Ann-Base-Multiplier Elements

Type Number Description none

Attributes

Name Type Description normal float Base multiplier for normal roads. highway float Base multiplier for highway. destination float Base multiplier for destination.

Ann-Base-Addition Elements

Type Number Description none

Attributes

Name Type Description normal float Base addition for normal roads. highway float Base addition for highway. destination float Base addition for destination.

Ann-Multiplier Elements

Type Number Description ann-multiplier- 3 Values for the announcement distance values multiplier. The first element is for normal street, second for highway and third for destination.

Attributes

Name Type Description none

Ann-Multiplier-Values Elements

Type Number Description none

Attributes

Name Type Description announce float Announce multiplier value. stacked-turn float Stacked turn multiplier value. lane-guidance float Lane guidance multiplier value. prepare float Prepare multiplier value. prepare-minimum float Prepare minimum multiplier value. turn float Turn multiplier value.

Nay-Guery Elements

The following optional elements are added to the query:

Type Number Description want-guidance- 0 . . . 1 If present, indicates that the client wants config to specify natural and lane guidance features. want-exit-numbers 0 . . . 1 If present, road exit names or numbers is added to the roadinfo element in the appropriate maneuvers.

Want-Guidance-Config Elements

Type Number Description want-enhanced- 0 . . . 1 If present, indicates that the client wants natural-guidance additional guidance points using NAVTEQ's Natural Guidance product. Note: The present invention is designed to work together with NAVTEQ's Natural Guidance, or independently therefrom. want-natural- 0 . . . 1 If present, indicates that the client wants guidance natural guidance using the present invention's guidance points. Note: The present invention is designed to work together with NAVTEQ's Natural Guidance, or independently therefrom. want-lane- 0 . . . 1 If present, indicates that the client wants guidance lane guidance information added to the appropriate maneuvers.

Attributes

Name Type Description

Nav-Maneuver Elements

The following elements are added to provide guidance point and lane guidance information.

Type Number Description guidance-point 0 . . . 2 These optional elements contain the information for guidance points (if available) associated with the maneuver. Note: these elements will only be present if want-NAVTEQ-natural-guidance or want-tcs-natural-guidance are specified in the nav-query. lane-info 0 . . . 1 This optional element contains the lane guidance information (if available) for this maneuver. Note: this element will only be present if want-lane-guidance is specified in the nav-query.

Attributes

Name Type Description

Guidance-point Elements

Type Number Description point 1 Position of the guidance point in coordinates, so it can be displayed on the map. use-for-prepare 0 . . . 1 If this element is present, this guidance point can be referenced in the Prepare to instruction. use-for-turn 0 . . . 1 If this element is present, this guidance point can be referenced in the Turn instruction.

Attributes

Name Type Description description string String containing the description of the guidance point. Examples: “red building”, “Mobil gas station”, “train tracks” gp-pronun string The pronunciation key for the guidance point description. gpprep-pronun string The pronunciation key for the preposition to use when referring to the guidance point. maneuver-point- float Distance to the maneuver point. If the offset guidance point is past the maneuver point, this should be zero.

Lane-Info Elements

The lane-info element provides a set of lane-guidance-item elements which are used to build the lane guidance display on the client.

Type Number Description lane-guidance-item 0 . . . n Lane guidance information is provided as a list of these items, each representing a line element at the maneuver point.

Attributes

Name Type Description number-of-lanes uint The number of lanes that are used in the maneuver. lane-position uint The position of the lanes starting from the leftmost lanes, 1-based. Example, if the road has 7 lanes and two lanes on the right (leaving the rightmost lane out) are used, then this will contain ‘5’ and number-of- lanes is 2 meaning lanes 5 and 6 are used for the maneuver. lgprep-pronun string Pronun key for the lane guidance preposition. Example: the. lg-pronun string Pronun key for the lane guidance instruction. Example: right-2-lane.

Lane-Guidance-Item Elements

Each guidance item comprises a lane type, an arrow type (which can be optionally highlighted), and a right divider item. Guidance items are specified from left to right.

Type Number Description lane-item 1 Provides the lane type. divider-item 1 Provides the divider type. arrow-item 1 . . . 2 The first element contains the non- highlighted arrow elements for this lane and the second one (if present) the highlighted arrow elements. Example: A lane may contain a straight- arrow and a slight-right-arrow and we want to indicate to the user device that it should take the slight right. So the first element will contain the non-highlighted straight-arrow and the second element will contain the highlighted slight-right- arrow.

Attributes

Name Type Description none

Lane-Item Elements

This element describes the type of lane to be used for this item. While NAVTEQ provides many different types of lanes in their database, Lane Guidance only uses a small subset thereof.

Type Number Description regular-lane 0 . . . 1 If present, this is a regular lane. hov-lane 0 . . . 1 If present, this is an HOV lane. reversible-lane 0 , , , 1 If present, this is a reversible lane. express-lane 0 . . . 1 If present, this is an express lane. acceleration-lane 0 . . . 1 If present, this is an acceleration lane. deceleration-lane 0 . . . 1 If present, this is a deceleration lane. auxiliary-lane 0 . . . 1 If present, this is an auxiliary lane. slow-lane 0 . . . 1 If present, this is a slow lane. passing-lane 0 . . . 1 If present, this is a passing lane. drivable-shoulder- 0 . . . 1 If present, this is a drivable shoulder lane lane. regulated-access- 0 . . . 1 If present, this is a lane with regulated lane access. turn-lane 0 . . . 1 If present, this is a turn lane. center-turn-lane 0 . . . 1 If present, this is a center turn lane. truck-parking-lane 0 . . . 1 If present, this is a truck parking lane. Note: the above elements can be combined, but not all combinations are allowed. See the lane types table for valid combinations.

Attributes

Name Type Description None

Divider-Item Elements

This element describes the type of divider to be used for this item. While NAVTEQ provides many different types of dividers in their database, Lane Guidance only uses a small subset thereof.

Type Number Description long-dash-divider 0 . . . 1 If present, this is a long dash divider. double-solid- 0 . . . 1 If present, this is a double solid divider. divider single-solid-divider 0 . . . 1 If present, this is a single solid divider. solid-dash-divider 0 . . . 1 If present, this is an inner solid outer dash divider. dash-solid-divider 0 . . . 1 If present, this is an inner dash outer solid divider. short-dash-divider 0 . . . 1 If present, this is a short dash divider. shaded-area- 0 . . . 1 If present, this is a shaded area divider. divider block-dash-divider 0 . . . 1 If present, this is a dashed block divider. physical-divider 0 . . . 1 If present, this is a physical divider. double-dash- 0 . . . 1 If present, this is a double dash divider. divider no-divider 0 . . . 1 If present, there is no divider. crossing-alert- 0 . . . 1 If present, this is a crossing alert divider. divider center-turn-line- 0 . . . 1 If present, this is a center turn line divider divider.

Attributes

Name Type Description None

Arrow-Item Elements

This element describes the type of lane to be used for this item. While NAVTEQ provides many different types of arrows in their database, Lane Guidance only uses a small subset thereof.

Type Number Description straight-arrow 0 . . . 1 If present, this is a straight arrow. slight-right-arrow 0 . . . 1 If present, this is a slight right arrow. right-arrow 0 . . . 1 If present, this is a right arrow. hard-right-arrow 0 . . . 1 If present, this is a hard right arrow. u-turn-left-arrow 0 . . . 1 If present, this is a u-turn left arrow. hard-left-arrow 0 . . . 1 If present, this is a hard left arrow. left-arrow 0 . . . 1 If present, this is a left arrow. slight-left-arrow 0 . . . 1 If present, this is a slight left arrow. merge-right-arrow 0 . . . 1 If present, this is a merge right arrow. merge-left-arrow 0 . . . 1 If present, this is a merge left arrow. merge-lanes-arrow 0 . . . 1 If present, this is a merge lanes arrow. u-turn-right-arrow 0 . . . 1 If present, this is a u-turn right arrow. second-right-arrow 0 . . . 1 If present, this is a second right arrow. second-left-arrow 0 . . . 1 If present, this is a second left arrow. Notes: arrow types can be combined, but not all combinations are valid.

Attributes

Name Type Description None

Roadinfo Elements

If want-exit-numbers element is present in the nay-query, then the roadinfo element may contain the following new element:

Type Number Description exit-number 0 . . . 1 This element contains the exit name or number for the maneuver.

Exit-Number Elements

Type Number Description none

Attributes

Name Type Description number string The exit name or number for this maneuver. Note: A road exit number can contain non-numeric values such as “13A”. pronun string The pronunciation key for the exit name or number.

Server-Based Configuration

All lane and natural guidance configuration is server-based. Some of the configuration values are for the routing engine, some for the server and some for the client. All configuration values are preferentially provided to allow for global updates (cross-platform and cross-version) with the ability of client-specific overrides if needed.

While the invention has been described with reference to the exemplary embodiments thereof, those skilled in the art are able to make various modifications to the described embodiments of the invention without departing from the true spirit and scope of the invention. 

What is claimed is:
 1. A method of providing natural navigational guidance to a user device, comprising: determining a natural guidance point selection area for an upcoming maneuver to be navigated; selecting a unique geographic feature within said determined natural guidance point selection area, as a natural guidance point for navigation of said upcoming maneuver; and generating a turn-type natural guidance point for an upcoming maneuver to be navigated, when said user device is within said natural guidance point selection area.
 2. The method of providing natural navigational guidance to a user device according to claim 1, further comprising: generating a prepare to-type natural guidance point outside said natural guidance point selection area when said natural guidance point is not used as a turn-type natural guidance point.
 3. The method of providing natural navigational guidance to a user device according to claim 1, wherein: said selection of said unique geographic feature is prioritized among available types of unique geographic features within said natural guidance point selection area.
 4. The method of providing natural navigational guidance to a user device according to claim 3, wherein said natural guidance point types comprise: a railroad track; a traffic light; a stop sign; an end of road; a bridge; and a street count.
 5. The method of providing natural navigational guidance to a user device according to claim 1, wherein: said geographic feature is selected in a decending order of priority among the following: a traffic light, a stop sign, an end of road, a railroad track, a bridge, and a street count.
 6. The method of providing natural navigational guidance to a user device according to claim 1, wherein: a priority of selection of said geographic feature is configurable in a server.
 7. The method of providing natural navigational guidance to a user device according to claim 1, further comprising: determining a point to begin providing natural guidance from said user device based on a type of said natural guidance point type.
 8. The method of providing natural navigational guidance to a user device according to claim 1, wherein: said user device is a smartphone.
 9. The method of providing natural navigational guidance to a user device according to claim 1, wherein: said user device is a tablet.
 10. The method of providing natural navigational guidance to a user device according to claim 1, wherein: said natural guidance point selection area does not include area behind a user device's current position and direction of travel.
 11. Apparatus for providing natural navigational guidance to a user device, comprising: means for determining a natural guidance point selection area for an upcoming maneuver to be navigated; means for selecting a unique geographic feature within said determined natural guidance point selection area, as a natural guidance point for navigation of said upcoming maneuver; and means for generating a turn-type natural guidance point for an upcoming maneuver to be navigated, when said user device is within said natural guidance point selection area.
 12. The apparatus for providing natural navigational guidance to a user device according to claim 11, further comprising: means for generating a prepare to-type natural guidance point outside said natural guidance point selection area when said natural guidance point is not used as a turn-type natural guidance point.
 13. The apparatus for providing natural navigational guidance to a user device according to claim 11, wherein: said means for selecting said unique geographic feature prioritizes said geographic features among available types of unique geographic features within said natural guidance point selection area.
 14. The apparatus for providing natural navigational guidance to a user device according to claim 13, wherein said natural guidance point types comprise: a traffic light; a stop sign; an end of road; a railroad track; a bridge; and a street count.
 15. The apparatus for providing natural navigational guidance to a user device according to claim 11, wherein: said means for selecting said unique geographic feature selects said unique geographic feature in a decending order of priority among the following: a railroad track, a traffic light, a stop sign, an end of road, a bridge, and a street count.
 16. The apparatus for providing natural navigational guidance to a user device according to claim 11, further comprising: means for determining a point to begin providing natural guidance from said user device based on a type of said natural guidance point type.
 17. The apparatus for providing natural navigational guidance to a user device according to claim 11, wherein: said user device is a smartphone.
 18. The apparatus for providing natural navigational guidance to a user device according to claim 11, wherein: said user device is a tablet.
 19. The apparatus for providing natural navigational guidance to a user device according to claim 11, wherein: said natural guidance point selection area does not include area behind a user device's current position and direction of travel. 